Characterization of an INVS Model IV Neutron Counter for High Precision ($\gamma,n$) Cross-Section Measurements

TL;DR

This paper details the precise characterization of an INVS Model IV neutron counter, adapted for high-accuracy ($ ext{γ,n}$) cross-section measurements near the neutron threshold, combining measurements and simulations to achieve ±3% efficiency accuracy.

Contribution

The study provides a comprehensive efficiency calibration of the neutron counter for ($ ext{γ,n}$) experiments, enhancing measurement precision and applicability across various targets.

Findings

Absolute detection efficiency determined within ±3% accuracy.

Efficiency characterization valid for neutron energies between 0.1 and 1 MeV.

Counter suitable for high-precision ($ ext{γ,n}$) cross-section measurements.

Abstract

A neutron counter designed for assay of radioactive materials has been adapted for beam experiments at TUNL. The cylindrical geometry and 60% maximum efficiency make it well suited for ($\gamma,n$) cross-section measurements near the neutron emission threshold. A high precision characterization of the counter has been made using neutrons from several sources. Using a combination of measurements and simulations, the absolute detection efficiency of the neutron counter was determined to an accuracy of $\pm$ 3% in the neutron energy range between 0.1 and 1 MeV. It is shown that this efficiency characterization is generally valid for a wide range of targets.